Pings sent by Glean

If data collection is enabled, the Glean SDKs provide a set of built-in pings that are assembled out of the box without any developer intervention. The following is a list of these built-in pings:

  • baseline ping: A small ping sent every time the application goes to foreground and background. Going to foreground also includes when the application starts.
  • deletion-request ping: Sent when the user disables telemetry in order to request a deletion of their data.
  • events ping: The default ping for events. Sent every time the application goes to background or a certain number of events is reached. Is not sent when there are no events recorded, even if there are other metrics with values.
  • metrics ping: The default ping for metrics. Sent approximately daily.

Applications can also define and send their own custom pings when the schedules of these pings is not suitable.

There is also a high-level overview of how the metrics and baseline pings relate and the timings they record.

Available pings per platform

SDKbaselinedeletion-requesteventsmetrics
Kotlin✅✅✅✅
Swift✅✅✅✅
Python✅ 1✅✅ 2❌
Rust✅✅✅✅
JavaScript❌✅✅❌
Firefox Desktop✅✅✅✅
1

Not sent automatically. Use the handle_client_active and handle_client_inactive API.

2

Sent on startup when pending events are stored. Additionally sent when handle_client_inactive is called.

Defining foreground and background state

These docs refer to application 'foreground' and 'background' state in several places.

Foreground

For Android, this specifically means the activity becomes visible to the user, it has entered the Started state, and the system invokes the onStart() callback.

Background

This specifically means when the activity is no longer visible to the user, it has entered the Stopped state, and the system invokes the onStop() callback.

This may occur, if the user uses Overview button to change to another app, the user presses the Back button and navigates to a previous application or the home screen, or if the user presses the Home button to return to the home screen. This can also occur if the user navigates away from the application through some notification or other means.

The system may also call onStop() when the activity has finished running, and is about to be terminated.

Foreground

For iOS, the Glean Swift SDK attaches to the willEnterForegroundNotification. This notification is posted by the OS shortly before an app leaves the background state on its way to becoming the active app.

Background

For iOS, this specifically means when the app is no longer visible to the user, or when the UIApplicationDelegate receives the applicationDidEnterBackground event.

This may occur if the user opens the task switcher to change to another app, or if the user presses the Home button to show the home screen. This can also occur if the user navigates away from the app through a notification or other means.

Note: Glean does not currently support Scene based lifecycle events that were introduced in iOS 13.